This invention relates to an electrically conductive resin composition capable of being baked at low temperature and having excellent heat resistance, moisture resistance and adhesion properties.
Known resin compositions capable of being baked at low temperature have been prepared by blending electrically conductive powder, such as carbon powder, copper powder or silver powder with a thermosetting resin, such as acrylic resin, alkyd resin, phenol resin, epoxy resin, polyimide resin and the like.
The present inventors have proposed an electrically conductive resin composition comprising a cyanate ester compound and a conductive powder, such as copper powder, copper alloy powder or silver powder (Refer to Japanese Patent Publication (kokai) No. 128504/1981). However, when electrically conductive resin compositions containing copper powder are heated, the copper powder is likely to be oxidized. So, resin compositions comprising a cyanate ester compound and copper powder were insufficient for use as a resin composition capable of being baked, due to oxidation of copper.
Processes for preventing deterioration in resin compositions through oxidation of copper by adding to the resin composition a reducing agent, such as formic acid, oxalic acid, adipic acid, benzoic acid, anthacene, anthranilic acid or anthrazine have been proposed (Refer to Japanese Patent Publication (kokai) Nos. 103260/1981; 163165/1981 and 163166/1981). However, it was found that when cyanate ester compound was used as resin component, deterioration in the resin composition and lowering of its electrical conductivity and its can-stability by heating it could not be prevented by adding such reducing agent to the resin composition.